This invention pertains to pistons, such as are used in gas compressors, pumps, and like equipments, which are formed in foundries by casting methods, and in particular to a cast, substantially hollow piston body, for a piston, of novel construction.
The known method of forming cast piston bodies, particularly cored piston bodies, comprises the forming of clean-out holes in the upper and lower ends or top and bottom walls of the piston body. After the interior of the piston body is satisfactorily cleaned, then its clean-out holes are machined to receive closure plugs. However, during use of the pistons which have these clean-out hole plugs therein, it happens that the plugs work free. The plugs have a tendency to loosen and remove from the holes. As a consequence, the gas compressor or pump in which these pistons are employed suffers grevious damage.
In view of the aforesaid problem with plugged clean-out holes in piston bodies, there obtains a need for an improved piston body. The need is for means which close off the clean-out holes, following clean-out of the piston body interior, which are not susceptible to displacement. In addition, it is also desirable to have piston bodies with generously large clean-out holes.
It is an object of this invention, then, to meet the aforecited need and, in so doing, define a piston body which has a great plurality of large clean-out holes formed therein.
Particularly, it is an object of this invention to set forth a cast, substantially hollow, piston body, comprising an annular outer wall; an annular, imperforate, top wall integral with said outer wall; an annular, imperforate, bottom wall integral with said outer wall; and an axial, central, piston rod-receiving bore; wherein said outer wall has a plurality of clean-out holes formed therein.